Apparatus for producing a three-dimensional workpiece

Abstract

An apparatus (10) for producing a three-dimensional workpiece (46) by irradiating a layer of a raw material powder with electromagnetic or particle radiation comprises a process chamber (16) accommodating a carrier (12) and a powder application device (14) for applying a layer of a raw material powder onto the carrier (12). The apparatus (10) further comprises an irradiation unit (26) for selectively irradiating the layer of the raw material powder with electromagnetic or particle radiation in accordance with a geometry of a corresponding layer of the workpiece (18) to be produced. An absorption device (50) adapted to absorb thermal radiation emitted when the layer of the raw material powder is selectively irradiated with electromagnetic or particle radiation is arranged in the process chamber (16) and / or the irradiation unit (26) in a position such that the absorption device is able to absorb radiation occurring inside the process chamber (16) and / or inside the irradiation unit (26).

Description

TECHNICAL FIELD

[0001] The present invention relates to an apparatus for producing a three-dimensional workpiece by irradiating layers of a feedstock powder with electromagnetic or particle radiation. BACKGROUND

[0002] Powder bed fusion is a layer-by-layer additive process by which a powdery feedstock, in particular a metallic and / or ceramic feedstock, can be processed into a three- dimensional workpiece of complex shape. To this end, a layer of feedstock powder is applied to a carrier and subjected to laser radiation in a position-selective manner according to the desired geometry of the workpiece to be produced. The laser radiation penetrating the powder layer causes heating and thus melting or sintering of the feedstock powder particles. Further layers of feedstock powder are then successively applied to the already laser-processed layer on the carrier until the workpiece has the desired shape and dimensions. Based on CAD data, powder bed fusion can be used for the production or repair of prototypes, tools, replacement parts, high-value parts or medical prostheses, for example dental or orthopedic prostheses.

[0003] An exemplary apparatus for producing a three-dimensional workpiece by powder bed fusion as described in EP 3 321 003 B1 comprises a process chamber accommodating a carrier for receiving a feedstock powder. An irradiation unit comprising a radiation source and a plurality of optical elements is provided to selectively irradiate electromagnetic or particle radiation onto the feedstock powder on the carrier for producing the workpiece. A protective gas stream is directed through the process chamber to establish a desired atmosphere within the process chamber and to expel impurities from the process chamber.

[0004] When establishing a three-dimensional workpiece on a carrier of a powder bed fusion apparatus, the radiation energy introduced into the feedstock powder causes the feedstock powder to melt and / or sinter. In particular, a melt pool of molten feedstock is generated in the area where the radiation beam impinges on the feedstock powder. The thermal radiation emitted from the irradiated powder bed can cause a temperature increase within the process chamber and thus also within the irradiation unit.

[0005] As described in EP 3 067 132 A1, temperature variations within the irradiation unit can cause temperature-dependent changes of specific optical properties of the optical elements of the irradiation unit. For example, the refractive index of an optical fiber, a lens or another optical element or the geometry of a lens, in particular the curvature or radius of a lens, can change depending on the temperature present within the process chamber and the irradiation unit. Due to the temperature-induced changes of the optical properties of the optical elements, the focus position of the radiation beam can be offset along the beam path of the radiation beam. SUMMARY

[0006] It is an object of the present invention to provide an apparatus for producing a high-quality three-dimensional workpiece by irradiating layers of a feedstock powder with electromagnetic or particle radiation.

[0007] An apparatus for producing a three-dimensional workpiece by irradiating layers of a feedstock powder with electromagnetic or particle radiation comprises a process chamber accommodating a carrier. The apparatus further comprises a powder application device for applying layers of the feedstock powder onto the carrier. In order to distribute the layers of the feedstock powder over the surface of the carrier, the powder application device can be moved across the carrier. The carrier can be a rigidly fixed carrier. However, preferably, the carrier is designed to be displaceable in a vertical direction, such that the carrier can be moved in the vertical direction downwards as the build height of the workpiece is increased while the workpiece is built up layer by layer from the feedstock powder. The feedstock powder applied onto the carrier is preferably a metal powder, in particular a metal alloy powder, but can also be a ceramic powder or a powder comprising different materials. The powder can have any suitable particle size or particle size distribution. However, preferably, a powder having a process particle size < 100 pm is processed. Preferably, the process chamber can be sealed against the ambient atmosphere.

[0008] The apparatus further comprises an irradiation unit for selectively irradiating the layers of the feedstock powder with electromagnetic or particle radiation in accordance with the geometry of the respective layer of the workpiece to be produced. The irradiation unit for selectively irradiating the layers of the feedstock powder with electromagnetic or particle radiation can comprise a radiation beam source, in particular a laser beam source, and additionally can comprise at least one optical unit for splitting, guiding and / or processing at least one radiation beam emitted by the radiation beam source. The optical unit can comprise optical elements such as an objective and a scanner unit, preferably the scanner unit comprises a diffractive optical element and a deflection mirror. The irradiation unit can irradiate the layers of the feedstock powder with a single radiation beam. However, it is also conceivable that the irradiation system irradiates two or more radiation beams onto the layers of the feedstock powder.

[0009] Absorption devices adapted to absorb radiation are arranged in the process chamber and / or the irradiation unit in a position such that the absorption devices are able to absorb radiation occurring inside the process chamber and / or inside the irradiation unit. An "absorption device" in the present application is a device that absorbs radiation, in particular thermal radiation, electromagnetic radiation and / or particle radiation, and thus causes said radiation to be discharged from components arranged in the vicinity of the absorption device. The thermal radiation to be absorbed by the absorption device can be emitted from the powder bed, the build part of the workpiece, the heating unit and further heated components. The electromagnetic radiation and / or particle radiation to be absorbed by the absorption device can be the radiation emitted in order to irradiate the layers of the feedstock powder. The electromagnetic radiation and / or particle radiation can in particular be reflected from the powder bed defined by the layers of the feedstock powder applied onto the carrier.

[0010] The phrase "in the processing chamber and / or irradiation unit" indicates that the absorption device is arranged within the interior space of the processing chamber and / or irradiation unit, and / or at least a portion of the absorption device is integrated into a component of the processing chamber and / or irradiation unit. For example, the absorption device may be at least partially integrated into the wall of the irradiation unit and / or processing chamber, or the absorption device may be at least partially arranged in an opening provided in the wall of the irradiation unit and / or processing chamber. The absorption device may also be at least partially integrated into a component of equipment for producing three-dimensional workpieces, which is arranged in the processing chamber and / or irradiation unit.

[0011] The absorption device may be defined by a single absorption element, which may be arranged in a processing chamber or irradiation unit. However, it is also conceivable that the absorption device includes multiple absorption elements, which may be distributed in the processing chamber and / or irradiation unit.

[0012] The absorption device absorbs radiation that would otherwise cause the optical elements of the irradiation unit to heat up. Therefore, the absorption device attenuates or even prevents temperature-induced changes in the optical properties of the irradiation unit's optical elements, as well as dislocations due to thermal deformation. This reduces or even avoids undesirable shifts in the focused position of the radiation beam along its beam path, i.e., shifts in the focused position along the z-axis. Similarly, undesirable shifts in the spot position of the radiation beam, i.e., shifts in the spot position along the x-axis and / or y-axis, can be reduced or even avoided. This makes it possible to produce high-quality workpieces that are less affected or even completely unaffected by the aforementioned temperature-induced focused position shifts.

[0013] The absorbing surface of the absorbing device can face the interior of the processing chamber and / or the interior of the irradiation unit. Therefore, the absorbing device is able to absorb radiation occurring inside the processing chamber and / or the irradiation unit in a particularly effective manner.

[0014] For thermal radiation, i.e., for radiation energy in the wavelength range from 0.75 μm to 50 μm, the absorbing surface of the absorbing device may have a hemispherical reflectance of less than 40%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5%. Alternatively or additionally, for radiation energy in the wavelength range of electromagnetic radiation or particle radiation used for selective irradiation of a layer of raw material powder, particularly in the wavelength range of 350 nm to 1100 nm, preferably 405 nm to 490 nm (blue light), 490 nm to 575 nm (green light), and / or 805 nm to 1100 nm (infrared), the absorbing surface of the absorbing device may have a hemispherical reflectance of less than 40%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5%.

[0015] Alternatively or additionally, the absorbing surface of the absorption device may be at least partially anodized, coated, foiled, oxidized, structured, and / or roughened, particularly by laser black marking. The anodized absorbing surface layer may have a thickness of 0.5 μm to 150 μm. The absorbing coating disposed on the absorption device and forming the absorbing surface of the absorption device may be a black and / or opaque coating or foil, similar to a black metallic or black ceramic coating or foil, and / or may have a thickness of 0.1 μm to 1 mm. The surface roughness of the absorbing surface may be in the range of 0.1 μm to 10 μm.

[0016] However, it is also conceivable that the hemispherical reflectivity of different absorbing surfaces can be different, especially that the hemispherical reflectivity of the absorbing surface in the processing chamber can be different from that of the absorbing surface in the irradiation unit. Preferably, the absorbing surface of the absorbing device arranged in the processing chamber is a good absorber for radiant energy at the wavelength of electromagnetic radiation or particle radiation selectively irradiating the layer of raw material powder, that is, radiant energy at the wavelength emitted from the radiation source of the irradiation unit. Alternatively or additionally, the absorbing surface of the absorbing unit arranged in the irradiation unit can be a good absorber for thermal radiation, that is, radiation in the wavelength range from 0.75 μm to 50 μm.

[0017] It is also conceivable that the absorbing device or its absorbing surface comprises or is made of a translucent material that absorbs radiant energy at wavelengths of electromagnetic radiation or particle radiation, particularly laser radiation, used for selective irradiation of the layer of raw material powder. For example, the absorbing surface of the absorbing device may comprise, or be made of, mineral glass or acrylic glass. The absorbing surface of the absorbing device may also be covered by a translucent window made of a non-absorbing material. A cooling channel may be defined between the absorbing surface and the translucent window. The cooling channel may be traversed by a coolant, which may be an absorbent coolant, such as water.

[0018] A reflective device suitable for reflecting radiation can be positioned in a processing chamber and / or irradiation unit such that it can reflect radiation occurring inside the processing chamber and / or irradiation unit. In this application, "reflective device" refers to a means of reflecting radiation (particularly thermal radiation, electromagnetic radiation, and / or particle radiation) and thus deflecting said radiation from components arranged near the reflective device. The reflective device may be defined by a single reflective element, which may be arranged in the processing chamber or irradiation unit. However, it is also conceivable that a reflective device comprises multiple reflective elements, which may be distributed within the processing chamber and / or irradiation unit.

[0019] Reflecting devices can be specifically positioned in the area of ​​the processing chamber and / or irradiation unit, where the emitted or reflected thermal radiation, electromagnetic radiation, and / or particle radiation emitted or reflected during the selective irradiation of the raw material powder layer with electromagnetic or particle radiation can strongly affect the optical properties of the optical elements of the irradiation unit, or intense heating can cause severe deformation. Furthermore, the reflecting devices can be arranged to reflect thermal radiation, electromagnetic radiation, and / or particle radiation back into the area of ​​the processing chamber and / or irradiation unit, wherein the radiation is less destructive and / or the radiation can be more easily dissipated. For example, the reflecting device can be positioned in the area of ​​the processing chamber adjacent to the irradiation unit, and the reflecting device can be arranged to reflect radiation away from the irradiation unit and along the direction of the carrier supporting the raw material powder layer to be irradiated.

[0020] The reflective surface of the reflector can face the interior of the processing chamber and / or the interior of the irradiation unit. Therefore, the reflector is able to reflect radiation occurring inside the processing chamber and / or the irradiation unit in a particularly effective manner.

[0021] For thermal radiation, i.e., for radiation energy in the wavelength range from 0.75 μm to 50 μm, the reflective surface of the reflective device may have a hemispherical reflectivity of greater than 60%, preferably greater than 70%, more preferably greater than 80%, and most preferably greater than 90%. Alternatively or additionally, for radiation energy in the wavelength range of electromagnetic radiation or particle radiation used for selective irradiation of the layer of raw material powder, particularly in the wavelength range of 350 nm to 1100 nm, preferably 405 nm to 490 nm (blue light), 490 nm to 575 nm (green light), and / or 805 nm to 1100 nm (infrared), the reflective surface of the reflective device may have a hemispherical reflectivity of greater than 60%, preferably greater than 70%, more preferably greater than 80%, and most preferably greater than 90%.

[0022] Alternatively or additionally, the reflective surface of the reflective device may be at least partially structured, foiled, coated, and / or polished. The reflective coating or foil disposed on the reflective device and forming the reflective surface of the reflective device may be specular and / or diffuse reflective. The reflective surface of the reflective device may be defined by a white, opaque coating or foil and / or may have a thickness of 0.01 μm to 1 mm. The surface roughness of the reflective surface may be less than 1 μm, preferably less than 0.2 μm.

[0023] However, it is also conceivable that the hemispherical reflectivity of different reflective surfaces can be different, particularly that the hemispherical reflectivity of the reflective surface in the processing chamber can differ from that of the reflective surface in the irradiation unit. Preferably, the reflective surface of the reflective device arranged in the processing chamber is a good reflector for radiant energy at wavelengths of electromagnetic radiation or particle radiation selectively irradiating the layer of raw material powder, i.e., radiant energy at wavelengths emitted from the radiation source of the irradiation unit. Alternatively or additionally, the reflective surface of the reflective device arranged in the irradiation unit can be a good reflector for thermal radiation, i.e., radiation at wavelengths ranging from 0.75 μm to 50 μm. The reflective surface in the processing chamber may also include retroreflector characteristics; for example, the reflective surface may include a retroreflector foil.

[0024] At least one of the absorbing and reflecting devices may contain a material with a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), and more preferably at least 100 W / (m*K). This ensures that heat is adequately dissipated from the absorbing and / or reflecting devices.

[0025] Besides the thermal conductivity of the absorbing and reflecting devices, the distances between the absorbing and reflecting surfaces, and the elements used to dissipate energy from the absorbing and reflecting devices, can be appropriately customized. The absorbing and reflecting devices can be made of different materials than the elements used to dissipate energy from them. Specifically, the length of the path for dissipating radiant energy and the thermal resistance along this path should be minimized, because the temperature difference between the heat source and the heat dissipation section depends on the heat flow and the overall auxiliary components along the dissipation path.

[0026] The absorption device may include at least one independent absorbing element arranged in a processing chamber and / or irradiation unit, the sole purpose of which is to absorb radiation emitted and / or reflected during selective irradiation of a layer of raw material powder with electromagnetic radiation or particle radiation. For example, the absorption device may include at least one plate-shaped absorbing element having a suitable absorbing surface.

[0027] Alternatively or additionally, the reflective device may include at least one independent reflective element arranged in the processing chamber and / or irradiation unit, the sole purpose of which is to reflect radiation emitted and / or reflected during selective irradiation of a layer of raw material powder with electromagnetic or particle radiation. For example, the reflective device may include at least one plate-shaped reflective element having a suitable reflective surface.

[0028] Alternatively or additionally, the absorption device may include at least one absorption element defined by a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall. For example, the absorption device may include at least one absorption element defined by a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall, the at least one absorption element being provided with an anodized, coated and / or roughened surface defining an absorption surface.

[0029] Furthermore, the reflecting device may include at least one reflecting element defined by a portion of the processing chamber wall and / or a portion of the irradiation unit housing wall. For example, the reflecting device may include at least one reflecting element defined by a portion of the processing chamber wall, a portion of the support structure of the irradiation unit, and / or a portion of the irradiation unit housing wall, the at least one reflecting element being provided with a coated and / or polished surface defining a reflecting surface.

[0030] The apparatus may also include a transmission element that enables the transmission of electromagnetic or particle radiation emitted by the irradiation device into the processing chamber. For example, the transmission element may be designed in the form of a window. Alternatively, the transmission element may comprise or consist of optical elements (especially lenses) of the irradiation device. The transmission element may be arranged in the walls of the processing chamber, particularly in the top wall portion of the processing chamber. In a particular preferred embodiment of the apparatus, the transmission element is arranged in a region above the center of the carrier. For example, the transmission element may be integrated into a wall portion, particularly in the top wall portion of the processing chamber.

[0031] The material of the transmission element can be selected based on the type of radiation emitted by the irradiation device to ensure the desired transmittance of the transmission element for electromagnetic or particle radiation emitted by the irradiation device. For example, the transmission element can be made of glass or a suitable polymer material. If desired, the transmission element can have a surface layer in a region of its surface facing the interior of the processing chamber, which minimizes the adhesion and deposition of welding fume condensate on the surface of the transmission element. In a particularly preferred embodiment of the apparatus, the transmission element is housed within at least a portion of the processing chamber wall that defines a reflective element. This processing chamber wall portion can be, for example, the top wall portion of the processing chamber.

[0032] The transmission element may include surface structures and / or coatings on one or more surfaces, particularly its entry surface and / or its exit surface. In a preferred embodiment, the transmission element may include an anti-reflective coating on its entry surface, i.e., the surface facing away from the processing chamber. Alternatively or additionally, the transmission element may include a reflective coating on its exit surface, i.e., the surface facing the processing chamber, to prevent overheating of the transmission element. For radiant energy in the wavelength range from 0.75 μm to 50 μm, the reflective coating on the exit surface of the transmission element may have a reflectivity greater than 40%, preferably greater than 50%, and more preferably greater than 60%. In another preferred embodiment, the transmission element (including optionally coated and / or structured surfaces) is configured to transmit at least 70% of the radiation, particularly at least 90%, in the direction from the surface to the surface. This radiation is at the wavelength of electromagnetic radiation or particle radiation used to selectively irradiate the layer of raw material powder, i.e., at the wavelength emitted by the radiation source of the irradiation unit, particularly at wavelengths ranging from 350 nm to 1100 nm, especially 405 nm to 490 nm (blue light), 490 nm to 575 nm (green light), and / or 805 nm to 1100 nm (infrared).

[0033] In a particular preferred embodiment of the apparatus, all suitable processing chamber wall portions subjected to thermal radiation emitted during selective irradiation of a layer of raw material powder by electromagnetic radiation or particle radiation define an absorbing or reflecting device. Hereinafter, the term "suitable processing chamber wall portions" refers to those processing chamber wall portions not used for another functional purpose (e.g., introducing or venting gas into or from the processing chamber, which makes the processing chamber wall portions unsuitable for defining an absorbing or reflecting device).

[0034] In a preferred embodiment of the apparatus, the processing chamber includes a first gas inlet for introducing gas, particularly an inert gas, into the processing chamber. For example, the first gas inlet may be defined by a porous processing chamber wall portion and / or by an opening provided in the processing chamber wall portion, particularly the processing chamber sidewall portion. The gas may be supplied by a first gas source, which may include a first gas storage container and a first gas supply line. The first gas source may be, for example, an argon source or a nitrogen source. The first gas supply line may be connected to the first gas inlet. The processing chamber may also be provided with a first gas outlet for discharging gas from the processing chamber.

[0035] A gas stream introduced into the processing chamber via a first gas inlet and discharged from the processing chamber via a first gas outlet can absorb and carry away particulate impurities (e.g., soot, welding fumes, powder particles, etc.) as it is guided through the processing chamber and, particularly, through the carrier, discharge these particulate impurities from the processing chamber. The first gas outlet and the first gas inlet can be connected to a recirculation line for recirculating the gas leaving the processing chamber via the first gas outlet back into the processing chamber via the first gas inlet. A suitable filter for filtering particulate impurities from the gas stream can be arranged in the recirculation line.

[0036] The first gas inlet can be configured to direct at least a portion of the gas flow introduced into the processing chamber via the first gas inlet to an absorption device and / or a reflection device arranged in the processing chamber, so as to transfer heat from the absorption device and / or the reflection device to the gas flow. Therefore, the gas flow can be used to cool the absorption device and / or the reflection device. The first gas source can be configured to provide cooled or heated gas. For this purpose, the first gas source can be in thermal contact with a first temperature control system configured to transfer heat to the gas to be introduced into the processing chamber or to exhaust heat from the gas to be introduced into the processing chamber.

[0037] During operation of the equipment and irradiation unit, in order to produce three-dimensional workpieces by irradiating layers of raw material powder with electromagnetic radiation or particle radiation, preferably, a first temperature control system is operated to cool the gas to be introduced into the processing chamber. Conversely, during the start-up phase of the equipment, before starting the irradiation unit and before commencing production of the three-dimensional workpiece, the first temperature control system can be operated to heat the gas to be introduced into the processing chamber, thereby heating the processing chamber and the components of the equipment that are in thermal contact with the processing chamber to a suitable operating temperature.

[0038] Preferably, the irradiation unit includes a second gas inlet for introducing gas, particularly an inert gas, into the irradiation unit. The gas can be supplied by a second gas source, which may include a second gas storage container and a second gas supply line. The second gas source may, for example, be a gas source that provides a gas with a high heat transfer coefficient without increasing the flow rate. In particular, the second gas source may be a helium source. The second gas supply line may be connected to the second gas inlet. The irradiation unit may also be provided with a second gas outlet for discharging gas from the irradiation unit. The second gas outlet and the second gas inlet may be connected to a recirculation line for recirculating gas leaving the irradiation unit via the second gas outlet back into the irradiation unit via the second gas inlet. Suitable filters, heat exchangers, and delivery devices may be arranged in the recirculation line. The delivery device may be designed in the form of a pump or compressor. The recirculation loop should be sealed to prevent loss of gas supplied by the second gas source, such as helium.

[0039] The second gas inlet can be configured to direct at least a portion of the gas flow introduced into the irradiation unit via the second gas inlet to an absorption device and / or a reflector arranged in the irradiation unit, so as to transfer heat from the absorption device and / or reflector to the gas flow. Therefore, the gas flow can be used to cool the absorption device and / or reflector. The second gas source can be configured to provide cooled or heated gas. For this purpose, the second gas source can be in thermal contact with a second temperature control system configured to transfer heat to or remove heat from the gas to be introduced into the irradiation unit.

[0040] During the operation of the equipment and irradiation unit, in order to produce three-dimensional workpieces by irradiating layers of raw material powder with electromagnetic radiation or particle radiation, preferably, a second temperature control system is operated to cool the gas to be introduced into the irradiation unit. Conversely, during the start-up phase of the equipment, before starting the irradiation unit and before commencing production of the three-dimensional workpiece, the second temperature control system can be operated to heat the gas to be introduced into the irradiation unit, thereby heating the irradiation unit and, in particular, the optical elements arranged within the irradiation unit to a suitable operating temperature.

[0041] The first gas inlet of the processing chamber and the second gas inlet of the irradiation unit can be connected to separate gas sources and / or separate temperature control systems for the processing chamber and irradiation unit as described above. However, it is also conceivable to provide only one gas source and / or one temperature control system for the equipment. Then, the first gas inlet of the processing chamber and the second gas inlet of the irradiation unit can be connected to the same gas source and / or the same temperature control system.

[0042] The absorption device may include a heat sink. Preferably, the heat sink of the absorption device extends from the absorption surface and / or the surface of the absorption device arranged opposite to the absorption surface. Thus, the heat sink is configured to guide heat away from the absorption device, particularly away from the absorption surface. When the absorption device includes one or more absorption elements, at least one of the absorption elements may be provided with a heat sink extending from the absorption surface and / or the surface of the absorption element arranged opposite to the absorption surface.

[0043] Alternatively or additionally, the reflecting device may include a heat sink. Preferably, the heat sink of the reflecting device extends from a surface of the reflecting device that is arranged opposite to the reflecting surface. Thus, the heat sink is configured to guide heat away from the reflecting device, particularly away from the reflecting surface. In cases where the reflecting device includes one or more reflecting elements, at least one of the reflecting elements may be provided with a heat sink extending from a surface of the reflecting element that is arranged opposite to the reflecting surface.

[0044] The absorption device may include at least one tempering channel, which extends through the body of the absorption device and / or extends to be adjacent to and in thermal contact with a surface of the absorption device arranged opposite to the absorption surface. In the case where the absorption device includes one or more absorption elements, at least one of the absorption elements may be provided with at least one tempering channel, which extends through the body of the absorption element and / or extends to be adjacent to and in thermal contact with a surface of the absorption element arranged opposite to the absorption surface.

[0045] Alternatively or additionally, the reflective device may include at least one tempering channel extending through the body of the reflective device and / or extending to be adjacent to and in thermal contact with a surface of the reflective device arranged opposite to the reflective surface. In cases where the reflective device includes one or more reflective elements, at least one of the reflective elements may be provided with at least one tempering channel extending through the body of the reflective element and / or extending to be adjacent to and in thermal contact with a surface of the reflective element arranged opposite to the reflective surface.

[0046] The tempering passage of the absorption and / or reflection device can be traversed by a suitable temperature-controlled fluid. The temperature-controlled fluid can be a liquid or gaseous fluid, such as air. The tempering passage of the absorption and / or reflection device can be in thermal contact with a third temperature control system configured to transfer heat to or remove heat from the temperature-controlled fluid flowing through the tempering passage.

[0047] During operation of the equipment and irradiation unit, in order to produce three-dimensional workpieces by irradiating layers of raw material powder with electromagnetic radiation or particle radiation, preferably, a third temperature control system is operated to cool the temperature control fluid flowing through at least one tempering channel of the absorption device and / or reflection device. Conversely, during the start-up phase of the equipment, before starting the irradiation unit and before commencing production of the three-dimensional workpiece, the third temperature control system may be operated to heat the temperature control fluid flowing through the tempering channel of the absorption device and / or reflection device, thereby heating the processing chamber and / or the components of the irradiation unit and equipment that are in thermal contact with the processing chamber and / or irradiation unit to a suitable operating temperature.

[0048] The third temperature control system can be integrated with the first and / or second temperature control systems. However, it is also conceivable to provide the equipment with a separate temperature control system for the gas supplied to the processing chamber and / or irradiation unit and the temperature control fluid flowing through the tempering passage of the absorption device and / or reflection device.

[0049] The apparatus may include at least one additional tempering channel. The at least one additional tempering channel may extend through a portion of the processing chamber wall and / or at least a portion of the irradiation unit housing wall that does not form an absorption device and / or a reflection device. Alternatively or additionally, the at least one additional tempering channel may extend adjacent to and in thermal contact with a portion of the processing chamber wall and / or at least a portion of the irradiation unit housing wall that does not form an absorption device or a reflection device.

[0050] The additional tempering channel can be traversed by a suitable temperature-controlled fluid. This temperature-controlled fluid can be a liquid or gaseous fluid, such as air. Preferably, the additional tempering channel is in thermal contact with a third temperature control system. Therefore, the temperature of the temperature-controlled fluid flowing through the additional tempering channel can be controlled in the same manner as the temperature-controlled fluid flowing through at least one tempering channel of the absorption and / or reflection device. However, it is also conceivable that the additional tempering channel is in thermal contact with a fourth temperature control system, which can control the temperature of the temperature-controlled fluid flowing through the additional tempering channel independently of the temperature of the temperature-controlled fluid flowing through at least one tempering channel of the absorption and / or reflection device.

[0051] At least one of the first, second, third, and fourth temperature control systems can be controlled by one or more temperature sensors that measure one or more of the surface temperature, gas flow temperature, and temperature control fluid temperature. Alternatively, at least one of the temperature control systems can be controlled based on construction operation data, particularly based on the proportion of the workpiece area to the powder bed to be irradiated.

[0052] The absorption device can be constructed and arranged for thermal expansion without imposing mechanical loads on the processing chamber and / or irradiation unit. Alternatively or additionally, the absorption device can be constructed and arranged for thermal expansion without affecting the position of the irradiation unit relative to the carrier.

[0053] This can be achieved, for example, by designing the absorber as an independent absorber element arranged in a manner that prevents thermal deformation of the absorber element from being transmitted to the processing chamber and / or irradiation unit. For instance, the absorber element can be freely suspended within the processing chamber and / or irradiation unit. Alternatively or additionally, the absorber can be connected to or integrated into the processing chamber and / or irradiation unit via an expansion joint that prevents thermal deformation of the absorber element from being transmitted to the processing chamber and / or irradiation unit.

[0054] A gap with a width of at least 0.1 mm can be provided between the outer wall of the irradiation unit facing the processing chamber or the support structure of the irradiation unit facing the processing chamber and the wall of the processing chamber facing the irradiation unit. For example, the irradiation unit may include a suitable support structure to arrange the irradiation unit, and particularly the outer wall of the irradiation unit facing the processing chamber, at a desired distance from the processing chamber. Therefore, the irradiation unit can be at least partially thermally separated from the processing chamber to prevent excess heat from being transferred from the processing chamber to the irradiation unit. The gap can be filled with a coolant, such as a cooled gas, and / or insulating material can be arranged within the gap.

[0055] The absorbing device may include at least one movable shielding element disposed within a processing chamber and associated with a functional tool housed within the processing chamber. Alternatively or additionally, the reflecting device may include at least one movable shielding element disposed within a processing chamber and associated with a functional tool housed within the processing chamber. For example, the movable shielding element of the absorbing or reflecting device may be associated with a powder application device, a glove extending into the processing chamber for manipulation purposes, and / or a suction device for discharging raw material powder from the processing chamber. The movable shielding element may be a simple plate-like element. However, it is also conceivable that the movable shielding element defines a housing for accommodating the functional tool. The movable shielding element protects the functional tool from radiation emitted and / or reflected during selective irradiation of a layer of raw material powder with electromagnetic radiation or particle radiation. Attached Figure Description

[0056] Preferred embodiments of the present invention will be described in more detail with reference to the accompanying schematic diagrams, in which:

[0057] Figure 1 An apparatus for producing three-dimensional workpieces by irradiating a layer of raw material powder with electromagnetic radiation or particle radiation is shown. Detailed Implementation

[0058] Figure 1 An apparatus 10 for producing three-dimensional workpieces via a layer-by-layer additive manufacturing process is shown. The apparatus includes a carrier 12 and a powder application device 14 for applying raw material powder onto the carrier 12. The carrier 12 and the powder application device 14 are housed within a processing chamber 16, which can be sealed relative to the ambient atmosphere. An internal atmosphere is established using a protective gas supplied via a first gas inlet 18 of the processing chamber 16. Figure 1 In the exemplary device 10 shown, a first gas inlet 18 is defined by a porous processing chamber wall portion 18a forming part of a processing chamber sidewall and an opening 18b formed in the processing chamber sidewall. Gas supplied to the processing chamber 16 via the first gas inlet 18 is provided by a first gas source 20, which includes a first gas storage container 22 and a first gas supply line 24. The first gas supply line 24 is connected to the first gas inlet 18.

[0059] The processing chamber 16 is also provided with a first gas outlet 25 for discharging gas from the processing chamber 16. During operation of the device 10, the gas flow introduced into the processing chamber 16 via the first gas inlet 18 and discharged from the processing chamber 16 via the first gas outlet 25 absorbs and carries away particulate impurities (e.g., soot, welding fumes, powder particles, etc.) as it is guided through the processing chamber 16 and across the carrier 12, and these particulate impurities are discharged from the processing chamber 16. The first gas outlet 25 and the first gas inlet 18 are connected to a recirculation line (not shown). Through the recirculation line, the gas leaving the processing chamber 16 via the first gas outlet 25 is recirculated back into the processing chamber 16 via the first gas inlet 18. A suitable filter (also not shown) for filtering particulate impurities from the gas flow can be arranged in the recirculation line.

[0060] The device 10 also includes an irradiation unit 26 for selectively irradiating the raw material powder applied to the carrier 12 with electromagnetic radiation or particle radiation. The irradiation unit 26 includes at least one radiation beam source, particularly a laser beam source. Figure 1 In the exemplary device 10 shown, a radiation source emits two radiation beams 30a and 30b, which are processed in a suitable manner by a pair of optical units 28. Each optical unit 28 includes optical elements (such as an objective lens and a scanner unit), the scanner unit including diffractive optical elements and / or at least one deflector.

[0061] Transmission elements 31, which allow the radiation beams 30a and 30b emitted by the irradiation device 26 to penetrate into the processing chamber 16, are arranged in the top wall portion of the processing chamber 16. A gap 33 with a width of at least 0.1 mm is provided between the portion of the irradiation unit outer shell wall 60 facing the processing chamber 16 and the portion of the processing chamber wall 58 facing the irradiation unit 26. In particular, the irradiation unit 26 includes a suitable support structure 35 to arrange the optical components of the irradiation unit 26, especially the portion of the irradiation unit outer shell wall facing the processing chamber 16, at a desired distance from the processing chamber 16. Therefore, the irradiation unit 26 is at least partially thermally separated from the processing chamber 16.

[0062] The irradiation unit 26 includes a second gas inlet 32 ​​for introducing inert gas into the irradiation unit 26. The inert gas is supplied by a second gas source 34, which includes a second gas storage container 36 and a second gas supply line 38. The second gas supply line 38 is connected to the second gas inlet 32. The irradiation unit 26 is also provided with a second gas outlet 40 for discharging gas from the irradiation unit 26.

[0063] The first gas source 20 and the second gas source 34 are configured to provide cooling or heating gases. For this purpose, the first gas source 20 is in thermal contact with a first temperature control system 42, which is configured to transfer heat to or remove heat from the gas to be introduced into the processing chamber 16. The second gas source 34 is in thermal contact with a second temperature control system 44, which is configured to transfer heat to or remove heat from the gas to be introduced into the irradiation unit 26.

[0064] During operation of the equipment 10 for producing the three-dimensional workpiece 46, a layer of raw material powder is applied to the carrier 12 by a powder application device 14. In order to apply the raw material powder layer, the powder application device 14 moves through the carrier 12. Then, according to the geometry of the corresponding layer of the workpiece 18 to be produced, the raw material powder layer is selectively irradiated by an irradiation device 26 using electromagnetic radiation or particle radiation.

[0065] The process involves repeatedly applying layers of raw material powder to the carrier 12 and selectively irradiating the layers of raw material powder with electromagnetic radiation or particle radiation according to the geometry of the corresponding layers of the workpiece 46 to be produced, until the workpiece 46 achieves the desired shape and size. The carrier 12 can be vertically displaced within the building cylinder 48, such that the carrier 12 can move downwards as the workpiece 48 is built up layer by layer on the carrier 12 with increasing workpiece building height. The carrier 12 may include a heater and / or a cooler.

[0066] During the operation of the equipment 10 and the irradiation unit 26, in order to produce the three-dimensional workpiece 48 as described above, the first temperature control system 42 and the second temperature control system 44 are operated to cool the gas to be introduced into the processing chamber 16 and the irradiation unit 26. Conversely, during the start-up phase of the equipment 10, before starting the irradiation unit 26 and before starting the production of the three-dimensional workpiece 48, the first temperature control system 42 and the second temperature control system 44 are operated to heat the gas to be introduced into the processing chamber 16 and the irradiation unit 26, thereby heating the processing chamber 16 and the irradiation unit 26 to a suitable operating temperature.

[0067] The device 10 also includes an absorption device 50 adapted to absorb radiation emitted and / or reflected during selective irradiation of a layer of raw material powder with electromagnetic radiation or particle radiation. Figure 1 In the diagram, the thermal radiation emitted when the raw material powder layer is selectively irradiated with electromagnetic radiation or particle radiation is schematically represented by the dot pattern inside the processing chamber 16, the gap 33 between the processing chamber 16 and the irradiation unit, and inside the irradiation unit 26.

[0068] The absorption device 50 includes a plurality of absorption elements 52a-e distributed in the processing chamber 16 and the irradiation unit 26. The absorption device 50 (i.e., each of the absorption elements 52a-e) is provided with an absorption surface 54, which has a hemispherical reflectance of less than 40%, preferably less than 20%, more preferably less than 10%, and most preferably less than 5% for radiant energy at wavelengths ranging from 0.75 μm to 50 μm and / or at wavelengths of electromagnetic radiation or particle radiation used for selective irradiation of layers of raw material powder, particularly ranging from 350 nm to 1100 nm, preferably 405 nm to 490 nm, 490 nm to 575 nm, and / or 805 nm to 1100 nm. Specifically, the absorption surface 54 of each of the absorption elements 52a-e is anodized or coated with a black and / or opaque metallic or ceramic coating to provide an anodized absorption surface layer or absorption coating with a thickness of 0.1 μm to 1 mm. The surface roughness of the absorbing surface is in the range of 0.1 μm to 10 μm. The absorbing device 50 (i.e., each of the absorbing elements 52a-e) contains a material with a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), and more preferably at least 100 W / (m*K).

[0069] Furthermore, the absorption surface 54 of the absorption device 50 (i.e., the absorption surface 54 of each of the absorption elements 52a-e) faces the interior of the processing chamber 16 or the interior of the irradiation unit 26.

[0070] Specifically, the absorption device 50 includes two independent absorption elements 52d and 52e, each comprising a plate-like body and arranged within the irradiation unit 26. The two absorption elements 52d and 52e are provided with heat sinks 56 extending from the surfaces of the absorption elements 52d and 52e that are arranged opposite to the absorption surface 54. Furthermore, the absorption device 50 includes an absorption element 52a defined by a portion of the processing chamber wall 58 and two absorption elements 52b and 52c defined by a portion of the support structure 35 of the irradiation unit 26. Each of the absorption elements 52a, 52b, and 52c includes a tempering channel 62 extending through the body of the absorption element 52a, 52b, and 52c. The absorption element 52a may be made of a translucent material. Additionally, the absorption element 52a may also be arranged in a recess formed in the processing chamber wall 58.

[0071] The apparatus 10 also includes a reflective device 64 adapted to reflect heat and laser radiation emitted and reflected during selective irradiation of a layer of raw material powder with electromagnetic radiation or particle radiation. The reflective device 64 comprises a plurality of reflective elements 66a-g distributed in the processing chamber 16 and the irradiation unit 26. The reflective device 64 (i.e., each of the reflective elements 66a-g) is provided with a reflective surface 68 having a hemispherical reflectivity greater than 60%, preferably greater than 70%, more preferably greater than 80%, and most preferably greater than 90% for radiant energy at wavelengths ranging from 0.75 μm to 50 μm and / or at wavelengths of electromagnetic radiation or particle radiation used for selective irradiation of the raw material powder layer, particularly ranging from 350 nm to 1100 nm, preferably 405 nm to 490 nm, 490 nm to 575 nm, and / or 805 nm to 1100 nm. Specifically, the reflective surface 68 of each of the reflective elements 66a-g is coated with a white, opaque coating or polished to provide a reflective coating with a thickness of 0.01 μm to 1 mm. The surface roughness of the reflective surface is less than 1 μm. The reflective device 64 (i.e., each of the reflective elements 66a-g) contains a material with a thermal conductivity of at least 10 W / (m*K), preferably at least 50 W / (m*K), and more preferably at least 100 W / (m*K).

[0072] Furthermore, the reflective surface 68 of the reflective device 64 (i.e., the reflective surface 68 of each of the reflective elements 66a-g) faces the interior of the processing chamber 16 or the interior of the irradiation unit 26.

[0073] Specifically, the reflecting device 64 includes reflecting elements 66a and 66b defined by a portion of the processing chamber wall 58, the portion having a reflective coating on its surface facing the interior of the processing chamber 16. Reflecting element 66b is defined by the top portion of the processing chamber wall 58 that houses the transmission element 31. Furthermore, the reflecting device 64 includes a reflecting element 66c defined by a portion of the support structure 35 of the irradiation unit 26, the portion having a reflective coating on its surface facing the processing chamber 16. Reflecting elements 66a-66c may include retroreflector characteristics, thus reflecting heat and laser radiation from the powder bed back to the powder bed.

[0074] Furthermore, the reflecting device 64 includes reflecting elements 66d and 66e defined by a portion of the irradiation unit housing wall 60, which has a reflective coating on its surface facing the interior of the irradiation unit 26, thereby causing thermal radiation to be further reflected away from the critical deformation portion of the irradiation unit housing wall 60 to less sensitive areas within the irradiation unit 26. Each of the reflecting elements 66b and 66c includes a tempering channel 70 extending through the body of the reflecting elements 66b and 66c. The reflecting device 64 also includes two separate reflecting elements 66g and 66f, which include plate-like bodies and are arranged within the irradiation unit 26. The two reflecting elements 66g and 66f are provided with heat sinks 56 extending from the surfaces of the reflecting elements 66g and 66f arranged opposite to the reflecting surface 68. The reflecting elements 66g and 66f may also include concave reflecting surfaces for dispersing the reflected radiation.

[0075] Finally, the reflective device 64 includes a movable shielding element 72, which is arranged in the processing chamber 16 and associated with a functional tool housed in the processing chamber 16. Figure 1 In the exemplary device 10 shown, the functional tool associated with the movable shielding element 72 is a powder application device 14. The movable shielding element 72 has a reflective coating on its outer surface to define a reflective surface 68.

[0076] The apparatus 10 includes an additional tempering channel 73 extending through a portion of the irradiation unit housing wall 60 that does not form at least a portion of the absorption device 50 and / or the reflector 64. The tempering channels 62, 70 of the absorption device 50 and the reflector 64, and the additional tempering channel 73, are traversed by a suitable temperature-controlled fluid and are in thermal contact with a third temperature control system 74, schematically shown. The third temperature control system 74 is configured to transfer heat to or remove heat from the temperature-controlled fluid flowing through the tempering channels 62, 70 and the additional tempering channel 73.

[0077] During the operation of the equipment 10 and irradiation unit 26, in order to produce the three-dimensional workpiece 46 by irradiating the layer of raw material powder with electromagnetic radiation or particle radiation, a third temperature control system 74 is operated to cool the temperature control fluid flowing through the tempering channels 62, 70 of the absorption device 50 and the reflection device 64 and the additional tempering channel 73. Conversely, during the start-up phase of the equipment 10, before starting the irradiation unit 26 and before starting the production of the three-dimensional workpiece 48, the third temperature control system 74 is operated to heat the temperature control fluid flowing through the tempering channels 62, 70 of the absorption device 50 and the reflection device 64 and the additional tempering channel 73, thereby heating the processing chamber 16 and the irradiation unit 26 to a suitable operating temperature.

[0078] To further control the temperature of the absorption device 50 in the reflective device 64, the first gas inlet 18 is configured to guide at least a portion of the gas flow introduced into the processing chamber 16 via the first gas inlet 18 to the absorption element 52, the reflective elements 66a, 66b, and the movable shielding element 72, so as to transfer heat from the absorption element 52, the reflective elements 66a, 66b, and the movable shielding element 72 to the gas flow. Therefore, the gas flow through the processing chamber 16 can be used to cool the components of the absorption device 50 and the reflective device 64 arranged in the processing chamber 16.

[0079] Similarly, the second gas inlet 37 is configured to direct at least a portion of the gas flow introduced into the irradiation unit 26 via the second gas inlet 37 to the absorbing elements 52c, 52d and the reflecting elements 66d-g, so as to transfer heat from the absorbing elements 52c, 52d and the reflecting elements 66d-g to the gas flow. Therefore, the gas flow can be used to cool the elements of the absorbing device 50 and the reflecting device 64 arranged in the irradiation unit 26.

Claims

1. An apparatus (10) for producing a three-dimensional workpiece (46) by irradiating a layer of raw material powder with electromagnetic radiation or particle radiation, said apparatus (10) comprising: Processing chamber (16) which contains a carrier (12) and a powder application device (14) for applying a layer of raw material powder onto the carrier (12); as well as Irradiation unit (26), the irradiation unit is used to selectively irradiate the layers of the raw material powder with electromagnetic radiation or particle radiation according to the geometry of the corresponding layer of the three-dimensional workpiece to be produced. The absorption device (50) suitable for absorbing radiation is disposed in the processing chamber (16) and / or the irradiation unit (26) in a position such that the absorption device can absorb radiation occurring inside the processing chamber (16) and / or the irradiation unit (26), and The absorption device (50) includes heat sinks (56) extending from the absorption surface (54) of the absorption device (50) and / or from the surface of the absorption device (50) arranged opposite to the absorption surface (54); and / or The absorption device (50) includes at least one first tempering channel (62) that extends through the body of the absorption device (50) and / or extends to be adjacent to and in thermal contact with the surface of the absorption device (50) that is arranged opposite to the absorption surface (54) of the absorption device (50).

2. The device (10) according to claim 1. - in, The absorption surface (54) of the absorption device (50) faces the interior of the processing chamber (16) and / or the interior of the irradiation unit (26); and / or - Wherein, for radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used for selective irradiation of the layer of said raw material powder, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 40%; and / or - wherein the absorption surface (54) of the absorption device (50) is at least partially coated, foiled, oxidized, structured and / or roughened.

3. The device (10) according to claim 1. in, A reflective device (64) suitable for reflecting radiation is disposed in the processing chamber (16) and / or the irradiation unit (26) in a position that enables the reflective device to reflect radiation occurring inside the processing chamber (16) and / or the irradiation unit (26).

4. The device (10) according to claim 3. - in, The reflective surface (68) of the reflective device (64) faces the interior of the processing chamber (16) and / or the interior of the irradiation unit (26); and / or - Wherein, for radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used for selective irradiation of the layer of said raw material powder, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 60%; and / or - wherein the reflective surface (68) of the reflective device (64) is at least partially structured, foiled, coated and / or polished.

5. The device (10) according to claim 3. in, At least one of the absorption device (50) and the reflection device (64) contains a material with a thermal conductivity of at least 10 W / (m*K).

6. The device (10) according to claim 3. - in, The absorption device (50) includes at least one independent absorption element arranged in the processing chamber (16) and / or the irradiation unit (26); and / or - in, The reflective device (64) includes at least one independent reflective element arranged in the processing chamber (16) and / or the irradiation unit (26).

7. The device (10) according to claim 3. - in, The absorption device (50) includes at least one absorption element defined by a portion of the processing chamber wall (58) and / or a portion of the irradiation unit housing wall (60); and / or - wherein the reflective device (64) includes at least one reflective element defined by a portion of the processing chamber wall (58), a portion of the support structure (35) of the irradiation unit (26) and / or a portion of the outer shell wall (60) of the irradiation unit.

8. The device (10) according to claim 3. The device also includes a transmission element (31) that enables electromagnetic radiation or particle radiation emitted by the irradiation unit (26) to be transmitted into the processing chamber (16).

9. The device (10) according to claim 1. in, The processing chamber (16) includes a first gas inlet (18) for introducing gas supplied by a first gas source (20) into the processing chamber (16). - Wherein, the first gas inlet (18) is configured to direct at least a portion of the gas flow introduced into the processing chamber (16) via the first gas inlet (18) to an absorption device (50) and / or a reflection device (64) arranged in the processing chamber (16) to transfer heat from the absorption device (50) and / or the reflection device (64) to the gas flow; and / or - wherein the first gas source (20) is configured to provide a cooling or heating gas.

10. The device (10) according to claim 1. in, The irradiation unit (26) includes a second gas inlet (32) for introducing gas supplied by a second gas source (34) into the irradiation unit (26). - Wherein, the second gas inlet (32) is configured to guide at least a portion of the gas flow introduced into the processing chamber (16) via the second gas inlet (32) to an absorption device (50) and / or a reflection device (64) arranged in the irradiation unit (26) to transfer heat from the absorption device (50) and / or the reflection device (64) to the gas flow; and / or - Wherein, the second gas source (34) is configured to provide a cooling or heating gas.

11. The device (10) according to claim 4. - in, The reflector (64) includes a heat sink (56).

12. The device (10) according to claim 4. - in, The reflector (64) includes at least one second tempering channel (70) that extends through the body of the reflector (64) and / or extends to be adjacent to and in thermal contact with the surface of the reflector (64) that is arranged opposite to the reflective surface (68).

13. The device (10) according to claim 1. - in, The absorption device (50) is constructed and arranged for thermal expansion without applying mechanical loads to the processing chamber (16) and / or the irradiation unit (26); and / or - The absorption device (50) is constructed and arranged to expand thermally without affecting the position of the irradiation unit (26) relative to the carrier (12).

14. The device (10) according to claim 1. in, A gap (33) with a width of at least 0.1 mm is provided between the portion of the outer wall (60) of the irradiation unit facing the processing chamber (16) or the support structure (35) of the irradiation unit (26) facing the processing chamber (16) and the portion of the processing chamber wall (58) facing the irradiation unit (26).

15. The device (10) according to claim 3. - in, The absorption device (50) includes at least one first movable shielding element arranged in the processing chamber (16) and associated with a functional tool housed in the processing chamber (16); and / or - The reflective device (64) includes at least one second movable shielding element (72) arranged in the processing chamber (16) and associated with a functional tool housed in the processing chamber (16).

16. The device (10) according to claim 1, wherein, For radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used to selectively irradiate the layer of said raw material powder, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 20%.

17. The device (10) according to claim 1, wherein, For radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used to selectively irradiate the layer of said raw material powder, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 10%.

18. The device (10) according to claim 1, wherein, For radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used to selectively irradiate the layer of said raw material powder, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 5%.

19. The device (10) according to claim 1, wherein, For radiant energy in the wavelength range of 350 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 40%.

20. The device (10) according to claim 1, wherein, For radiant energy in the wavelength range of 350 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 20%.

21. The device (10) according to claim 1, wherein, For radiant energy in the wavelength range of 350 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 10%.

22. The device (10) according to claim 1, wherein, For radiant energy in the wavelength range of 350 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 5%.

23. The device (10) according to claim 1, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm, and / or from 805 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 40%.

24. The device (10) according to claim 1, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm, and / or from 805 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 20%.

25. The device (10) according to claim 1, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm, and / or from 805 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 10%.

26. The device (10) according to claim 1, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm, and / or from 805 nm to 1100 nm, the absorbing surface (54) of the absorbing device (50) has a hemispherical reflectivity of less than 5%.

27. The device (10) according to claim 1, wherein, The absorption surface (54) of the absorption device (50) is at least partially anodized.

28. The device (10) according to claim 1, wherein, The absorption surface (54) of the absorption device (50) is at least partially marked with laser black.

29. The device (10) according to claim 3, wherein, For radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used to selectively irradiate the layer of said raw material powder, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 70%.

30. The device (10) according to claim 3, wherein, For radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used to selectively irradiate the layer of said raw material powder, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 80%.

31. The device (10) according to claim 3, wherein, For radiation energy at wavelengths ranging from 0.75µm to 50µm and / or at wavelengths of electromagnetic radiation or particle radiation used to selectively irradiate the layer of said raw material powder, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 90%.

32. The device (10) according to claim 3, wherein, For radiant energy in the wavelength range from 350 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 60%.

33. The device (10) according to claim 3, wherein, For radiant energy in the wavelength range from 350 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 70%.

34. The device (10) according to claim 3, wherein, For radiant energy in wavelengths ranging from 350 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 80%.

35. The device (10) according to claim 3, wherein, For radiant energy in wavelengths ranging from 350 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 90%.

36. The device (10) according to claim 3, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm and / or from 805 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 60%.

37. The device (10) according to claim 3, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm, and / or from 805 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 70%.

38. The device (10) according to claim 3, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm and / or from 805 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 80%.

39. The device (10) according to claim 3, wherein, For radiant energy at wavelengths ranging from 405 nm to 490 nm, from 490 nm to 575 nm and / or from 805 nm to 1100 nm, the reflective surface (68) of the reflective device (64) has a hemispherical reflectivity greater than 90%.

40. The device (10) according to claim 3, wherein, At least one of the absorbing device (50) and the reflecting device (64) contains a material with a thermal conductivity of at least 50 W / (m*K).

41. The device (10) according to claim 3, wherein, At least one of the absorption device (50) and the reflection device (64) contains a material with a thermal conductivity of at least 100 W / (m*K).

42. The device (10) according to claim 8, wherein, The transmission element (31) is housed in the portion of the processing chamber wall (58) that defines the reflective element of the reflective device (64).

43. The device (10) according to claim 11, wherein, The heat sink (56) extends from the surface of the reflective device (64) that is arranged opposite to the reflective surface (68).

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